1. Field of the Invention
The invention relates to methods and arrangements for distinguishing between target areas and non-target areas during a laser surgical procedure, by coating or otherwise providing the non-target areas with a phosphorescent material or phosphor.
The target areas may be any tissue or object at which the laser is directed. The non-target areas to which the phosphors are applied may include, but are not limited to, any portion of a scope or laser delivery apparatus, including a laser sheath, buffer material of the fiber, endoscope working channel, and cardiac or urological stents, as well as tissues in the vicinity the target.
The phosphors applied to or providing in the non-target areas include any materials that, when exposed to a particular wavelength, emit light at a different wavelength. In one embodiment, the phosphors may be rare-earth nanophosphors that up-convert IR wavelengths to visible or near visible wavelengths, and therefore provide a detectable indication of overheating in the area of the target.
However, the invention is not limited to up-conversion of IR wavelengths, or to emissions in the visible or near visible wavelengths, but also may include materials that down-convert higher wavelengths to visible or near visible, and to phosphors that emit IR or UV rather than visible or near-visible radiation. The phosphors may also be used for monitoring purposes other than overheating detection. For example, phosphors may be included in the fiber itself, and in particular the cladding and/or buffer, to be used as an indicator of excess energy absorption in the cladding or buffer. Furthermore, multiple different types of phosphors may be provided in a particular application to carry out different monitoring functions.
The phosphor emissions may be monitored in a variety ways, including automated wavelength or frequency detection, as well as observation of visible wavelengths by an operator or clinician. In addition, analysis techniques may include frequency domain (Fourier) analysis and other complex signal analyzing techniques.
2. Description of Related Art
Copending U.S. patent application Ser. No. 13/127,911 (PCT Pub. WO 2010/053575) describes feedback systems described therein are used in connection with sacrificial elements or coatings that absorb selected wavelengths of radiation emitted during a surgical procedure, and that in response heat up or emits radiation in a way that can more easily and reliably be detected by the treatment site monitoring arrangement. The present invention is based on similar principles, but the phosphors of the present invention are not intended to be sacrificed, but rather are detected based solely on frequency conversion or fluorescence signature.
Copending U.S. patent application Ser. No. 13/070,247 (U.S. Pub. 2011/0238048) is also of interest since it discloses distinguishing radiation emitted as a result of fiber breakdown from radiation reflective of a normal surgical procedure based on radiation event counts. The present application provides an alternative and more versatile way of distinguishing between events, although it can also be combined with the count procedure of the copending application.
In addition to disclosure of various techniques and arrangements for distinguishing between target and non-target emissions at a treatment site, the inventor has proposed a variety of treatment-monitoring feedback systems that can detect the wavelength, amplitude, or timing of radiation that originate at the surgical site, including feedback systems capable of analyzing the frequency spectrum of emissions. Examples of feedback systems that can be used with the method and apparatus of the invention are described in copending U.S. patent application Ser. Nos. 11/714,785 (U.S. Pub. 2007/0167937), 12/073,922 (U.S. Pub. 2009-0149845), 13/070,247, and 13/127,911 (PCT Pub. WO 2010/053575), each of which is incorporated by reference herein.